Police patrol a checkpoint in Russia's Dagestan Province after a deadly suicide blast there on Thursday.
The explosion killed three police offers and wounded another six, ripping a 4-metre hole in the checkpoint headquarters.
The bomber detonated explosives in a car as police tried to stop the vehicle on its way through the checkpoint.
One person is still unaccounted for.
Tensions are high in Russia's predominately Muslim North Caucasus region, as Islamist insurgents wage daily violence in a fight to establish an Islamist state.
Dagestan has emerged as the epicentre of violence.
The suicide bombing follows a police raid on a forest hideout that killed five militants earlier this week in Dagestan.